Wand of cold

The wand of cold shoots bolts of ice, dealing 6d6 damage to non-cold resistant targets. The beam bounces when it hits walls or targets with reflection.

No levitation or water walking? A wand of cold with sufficient charges can be a last resort if you need to cross the water on Medusa's Island. The bolt will freeze any square of water that it crosses. You can use this to build and extend ice bridges. Try to use the shortest bridges possible. Even if you only had one wand, you might still make it, even if you have to wrest that last charge by repeatedly zapping the empty wand. If you have a frost horn, you can use that instead. Be careful of monsters with fire attacks, though!